<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>flex子项</title>
    <style>
        div {
            display: flex;
            width: 60%;
            height: 300px;
            background-color: beige;
            margin: 0 auto;
            flex-flow: row wrap;
            /* justify-content: space-between; */
            align-items: center;
        }
        span {
            /* flex: 30%; */
            width: 150px;
            height: 100px;
            background-color: thistle;
        }
        span:nth-child(1) {
            background-color: turquoise;
        }
        span:nth-child(2) {
            /* flex: 5; */
            background-color: thistle;
            /* order: -2; */
        }
        span:nth-child(3) {
            background-color: turquoise;
            /* align-self: flex-start; */
            /* order: -1; */
        }
    </style>
</head>
<body>
    <div>
        <span>1</span>
        <span>2</span>
        <span>3</span>
        <span>4</span>
        <!-- <span>5</span> -->
    </div>
</body>
</html>